Behind this effect would be the chemical compound As01, which is present in both immunizers and has already been associated with brain protection in previous research
A study in June 2025 in the magazine NPJ Vaccines It reveals that immunizers used to combat VZV (chickenpox) and VSR (respiratory virus) infections can reduce the risk of dementia. The first virus is known to cause chicken pox and herpes zoster, while the second leads to lightweight respiratory paintings in adults, with symptoms similar to those of a cold, and bronchiolitis in children.
Research, by researchers at Oxford University in the UK, suggests that one of the reasons behind this effect may be the “As01”, an adjuvant chemical compound that is often implemented by pharmaceuticals to enhance the immune response of these vaccines.
Previous studies with mice, published in e they had already indicated that the AS01 may be related to reducing the accumulation of amyloid plates, toxic fragments of proteins that form in the brain of people with Alzheimer. Other research has shown that the VZV vaccine would have a protective effect against dementia.
In Oxford’s investigation, the goal was to verify whether this consequence was specifically linked to this immunizer or other factors of its formulation. This is why the team decided to compare immunized individuals against the Zoster and others vaccinated against the VSR, whose vaccine also has the adjuvant as01.
Scholars analyzed medical record data from over 436,000 patients 60 or older, available in the US Electronic Health Registry, Trinestx. In total, scientists compared the risk of dementia among people of 4 groups: vaccinated only against chickenpox, only against the VSR, immunized for both viruses and those who did not receive any of the two vaccines.
The results showed significant reductions in the likelihood of detecting a neurodegenerative disease in the 18 months following the application of immunizers. Vaccinated against VSR, for example, demonstrated a 29% lower risk of developing dementia. Already among those immunized only for the zoster, this reduction was 18%. In the case of those who received both vaccines, the probability was 37% lower.
“The study also found that the reduction of dementia happens regardless of the frequency of infection, since the protective effect of the two vaccines could already be observed 3 months after the application – as the immunizer takes to begin to prevent the viruses.”says neurologist Livia Almeida Dutra, coordinator of the Brain Institute of Israeli Hospital Albert Einstein.
Results are not definitive
Caution is needed when analyzing these findings. “This is not a causal study, which means that its results do not clarify all the mechanisms involved in the observed effect. It is even possible that the reduction of dementia is a multifactorial consequence, not restricted to the AS01”says Dutra. “On the other hand, it adds scientific data to an existing discussion about the role of As01 in the treatment of Alzheimer’s”complete.
As research is based on the review of medical records, clinical trials are still required to analyze more depth if there were different variables from the vaccine that are associated with reduced risk of dementia.
In addition to better understanding the AS01 acting mechanisms, the authors say that it would also be necessary to understand the duration of this possible beneficial effect.
Get to know the vaccines
The herpes-zoster vaccine is not available in the SUS (Unified Health System), but can be found in the private network. Its application follows a regime of two doses, with indication for adults over 50 years.
The immunizer against VSR, which is also available in the private sector, was incorporated into SUS announced in February 2025 by the Ministry of Health. The Pfizer Pharmaceutical Abrysvo vaccine will be made available to pregnant women who pass antibodies to the fetus.
Applied to only one dose, it can be given from 24th to 36th weeks of gestation. But it is recommended that immunization be performed at least two weeks before delivery to ensure protective effects.
There is also the option of VSR vaccination for the elderly. Available for this private network, Abrysvo and Arexvy Immunizers (from British GSK) are applied at a single dose. They are available to people aged 60 to 69 who have comorbidities and for all from 70 years.
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